Valve for vehicle suspension system



Aug. 17, 1965 G. w. JACKSON 3,200,343

VALVE FOR VEHICLE SUSPENSION SYSTEM Original Filed Sept. 12, 1960 2Sheets-Sheet 1 7. INVENTOR. 'earye [41 Jackson 2:; z. AH

H18 477' R'NEY Aug. 17, 1965 G. w. JACKSON VALVE FOR VEHICLE SUSPENSIONSYSTEM Original Filed Sept. 12, 1960 2 Sheets-Sheet 2 INVENTOR. 'earye(1/. Jackson BY w United States Patent 0 3 Claims. or. tar-614.19

This invention relates to an automotive vehicle suspension systemincorporating a combination shock absorber and supplementary air springunit assembly that is adapted to be placed between the sprung mass andthe unsprung mass of a vehicle adjacent the main suspension spring forthe vehicle that is also placed between the sprung mass and the unsprungmass of the vehicle with the combination shock absorber andsupplementary air spring unit assembly being disposed in the sameposition normally occupied by a conventional direct-acting tubular typeshock absorber so that when the supplementary air spring unit ispressurized with a suitable fluid under pressure, such as air, thesupplementary air spring unit will aid the main suspension spring insupport of the sprung mass of the vehicle on the unsprung mass.

This application is a division of Serial No. 55,359 filed September 12,1960, now abandoned.

The main suspension springs for the vehicle are engineered to providethe desired suspension normally provided between the sprung mass and theunsprung mass of a vehicle, the main suspension springs being engineeredto give the ride effect desird in th vehicle. Normally a direct-actingtubular type shock absorber is positioned between the sprung mass andthe unsprung mass of the vehicle adjacent the main suspension spring todamp movements between the sprung mass and the unsprung mass of thevehicle.

In this invention a direct-acting tubular type shock absorber isprovided with a supplementary air spring unit which forms with the shockabsorber an assembly that is adapted to be placed between the sprungmass and the unsprung mass of the vehicle in the same position normallyoccupied by the conventional directacting tubular type shock absorber.The supplementary air spring unit is adapted to be operated either in adeflated condition or in an inflated condition depending upon whether ornot supplementary or aiding support is required between the sprung massand the unsprung mass of the vehicle to maintain the vehicle in a levelcondition relative to the road, depending upon the load carried in thevehicle.

Under all normal operating conditions the vehicle is designed to carryan average load condition of passengers and baggage, but even underthese conditions there are times when the passenger load and the baggageload becomes heavy so that the rear end of the vehicle tends to sag.Under these conditions, or under extra heavily loaded conditions, suchas when a boat or house trailer is being drawn by the vehicle, thesupplementary air spring, that is around the shock absorber can bepressurized with a suitable fluid under pressure, such as air, toprovide an air spring unit that will yieldingly support or help supportthe added load and thereby aid the main suspension spring in theyielding support of the sprung mass on the unsprung mass of the vehicle.

Under conditions of operation of the vehicle wherein the supplementaryair spring unit is not required to give any substantial aid to the mainsuspension spring of the vehicle, the supplementary air spring unit willoperate in a deflated condition so that the flexible walls of which itis constructed tend to abrade one another in their movement ofreciprocation with the reciprocal movement of the telescoping parts ofthe shock absorber. To conserve space, at least a part of the wallstructure of the air spring unit is formed as a flexible tubular Wallstructure comprising inner and outer wall portions interconnected by areturn bend portion, the inner and outer wall portions of the tubularwall section of the supplementary air spring unit tending to ride uponone another in the telescoping movement or reciprocating movement of theshock absorber parts. This abrading section between the flexible wallsof the tubular Wall portion of the air spring unit tends to reduce thelife of the Wall structure as well as cause the wall portion to bendover a much sharper radius in the return bend portion than when the airspring unit is being operated in an inflated condition.

It is therefore an object of this invention to provide an automotivevehicle suspension system incorporating a combination shock absorber andsupplementary air spring unit assembly operating in parallel relationwith the main suspension spring for support of the sprung mass on theunsprung mass of the vehicle and adjacent the main spring of the vehiclethat includes controls to maintain a predetermined minimum inflationpressure within the supplementary air spring unit that is justsuflicient to slightly inflate the portion of the air spring unit thatis formed of the flexible tubular walls to prevent the flexible wallsfrom engaging one another during reciprocal movement f the shockabsorber parts and corresponding reciprocal movement of the air springparts.

It is another object of the invention to provide an automotive vehiclesuspension system in accordance with the foregoing object wherein thecontrols for the system include a control member that is manuallyoperated to inflate the supplementary air spring unit and to deflate thesame in accordance with the desire of the operator of the vehicle, butwherein there is also included an automatic control which cuts off theexhaust of fluid pressure from the air spring unit when a predeterminedminimum pressure has been reached in the air spring unit duringexhausting of the unit so that there will always be a predeterminedminimum pressure retained in the supplementary air spring at all times.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawings wherein preferred embodiments of the present invention areclearly shown.

In the drawings:

FIGURE 1 is a schematic cross-sectional view of a vehicle incorporatinga combination shock absorber and supplementary air spring unit assemblydisposed adjacent each of the main suspension springs of the vehicle aslocated at the rear end of the vehicle adjacent the main springs andadjacent the axle, the air springs being connected with controls forcontrolling exhaust and supply of air to the air springs.

FIGURE 2 is a schematic longitudinal cross-sectional view of a vehicleillustrating the assembly shown in FIG- URE 1.

FIGURE 3 is a longitudinal cross-sectional view of a combination shockabsorber and supplementary air spring unit assembly that is used in theautomotive vehcile suspension system shown in FIGURES l and 2.

FIGURE 4 is a longitudinal cross-sectional view of a control valveincorporated in the supplementary air spring portion of the suspensionsystem shown in FIG- URES l and 2.

In this invention, in FIGURES 1 and 2, there is illustratedschematically an automotive vehicle suspension system incorporating thefeatures of this invention. The motor vehicle 10 has a chassis frame 11that forms the sprung mass of the vehicle, together with the body of thevehicle, that is supported on the axle structure 12 having thedifferential 13 and the wheels 14 and 15 that are laterally spaced onthe axle, the axle structure and the wheels forming the unsprung mass ofthe vehicle. The main suspension springs 16 and 17 are attached to theaxle 12 in a conventional manner with the ends of the springs 16 and 17each being connected with the chassis frame 11 by means of supportshackles 18 and 19 placed at opposite ends of the leaf springs 16 and17.

A combination shock absorber and supplementary air spring unit 20 isplaced between the attachment support 21 for the spring 17 and thechassis 11, the combination shock absorber and air spring unit beingdisposed adjacent the main suspension spring 17 and being adapted tooperate in parallel support relation effort to resiliently support thechassis 11 on the axle structure of the vehicle. A similar combinationshock absorber and air spring unit 200 is located between the supportbracket 22 for the spring 16 and the chassis 11 in the same manner asthe 'unit 26. When the air spring units 25 and 25a are inflated in amanner hereinafter described, the air spring units aid support of thesprung mass or chassis 11 on the unsprung mass or axle structure 12 toprevent rear end sagging of the vehicle, the shock absorber of each ofthe combination units 20 and 20a functioning as a conventionaldirect-acting tubular type shock absorber.

The combination direct-acting tubular type shock absorber and air springunit assembly is more particularly illustrated in FIGURE 3, each of theunits 20 and 20a being of like structure, as shown in FIGURE 3.

As illustrated in FIGURE 3, the combination shock absorber and airspring unit assembly consists of a shock absorber 3t and the air springunit 25 that is carried on the shock absorber. The shock absorberconsists of a pressure cylinder 31 having a valved piston 32 that iscarried on the end of a reciprocating rod 33. The reciprocating rod 33extends through a rod guide member 34 at one end of the pressurecylinder 31, the rod guide member 34 having a rod seal chamber 35 thatreceives a rod seal 36 engaging the rod 33 and sealing against loss ofhydraulic fluid from within the pressure cylinder 31. The projecting endof the rod 33 carries a fitting 37 that is adapted to be attached to thesprung mass or chassis 11 of the vehicle for attaching this end of theshock absorber to the vehicle. The seal chamber 35 is closed by a capmember 38 that also holds the rod seal 36 within the chamber 35, acompression spring 39 retaining resilient pressure on the seal member 36to retain it in sealing engagement with the surface of the reciprocalrod 33.

The lower end of the pressure cylinder 31 is closed by a base valvestructure 40 so that a compression chamber 41 is formed between the basevalve 40 and the piston 32. A rebound chamber 42 is formed between thepiston 32 and the rod guide 34 at the upper end of the pressure cylinder31. The piston 32 is provided with a compression control valve 43 on oneside of the piston to regulate flow of hydraulic fluid from the chamber41 into the chamber 42 on movement of the piston 32 toward the basevalve 40, excess fluid produced by the entry of rod 33 into the chamber42 being displaced through the base valve 40 into the reservoir chamberaround the pressure cylinder 31. On the opposite side of the piston 32there is provided the rebound control valve 24 that regulates flow ofhydraulic fluid from chamber 42 into chamber 41 when the piston movesupwardly away from the base valve 20, additional fluid for filling thechamber 41 being obtained from the reservoir through the base valve 40.

The base valve 40 is carried in a closure cap 45 that is secured withinone end of a reservoir tube 46 surrounding and spaced from the pressurecylinder tube 31. The upper end of the reservoir tube 46 is fixedlyattached to the clousrue cap 38, thereby providing a closed fluidreservoir space 47 between the pressure cylinder tube 31 and thereservoir tube 46. The base valve 40 has a valve member 43 that controlsflow of hydraulic fluid from the compression chamber 41 into thereservoir chamber 47 on movement of the piston 32 toward the base valve40. The base valve also includes a valve member 49 that provides forrelatively free flow of hydraulic fluid from the reservoir chamber 47back into the compression chamber 41 on movement of the piston 32 awayfrom the base valve.

The closure cap 45 carries a fitting 50 that is adapted to attach thelower end of the shock absorber to the unsprung mass or axle structure12 of the vehicle, the fitting members 5t) and 37 thereby attaching thecombination shock absorber and air spring unit assembly 20 and 20abetween the sprung mass and the unsprung mass of the vehicle, in whichcondition the shock absorber 30 can function in conventional manner toprovide for damping of relative movement between the sprung mass and theunsprung mass of the vehicle.

The air spring unit assembly 25 of the combination structure includes atubular wall 51 that surrounds the reservoir tube 46 and is spaced fromthe tube and is coaxial with the axis of the shock absorber. The upperend of this tubular member 51 is secured to a cap member- 52 that, inturn, is secured to the upper end 53 of the rod 33, the cap 52 and thetubular member 51 forming a chamber space 54 having an open end 55.

The open end 55 of the chamber space 54 is closed by a double-walledflexible tubular structure that includes an inner wall portion 61 and anouter wall portion 62 connected together by a return bend portion 63integral with the wall portions 61 and 62, and is formed by theseportions on relative reciprocation between the inner and the outer Wallportions 61 and 62.

The inner wall portion 61 is sleeved onto the reservoir tube 46 and hasa free end portion 64 that is attached to the rservoir tube 46frictionally by an attaching sleeve 65.

The reservoir tube 46 has a cylindrical wall portion 66 coaxial with theaxis of the shock absorber from the upper end of which there extends awall portion 67 that has a diameter that diminishes continuously as thewall portion extends upwardly from the line X, the wall portion 67 beingin the form of a truncated cone the base of which joins with thecylindrical wall portion at the line X. The wall portion 66 has a wallportion 68 extending downwardly therefrom that is of a diameter thatincreases continuously from the line Y to form a shoulder by the wallportion 68. The cylindrical sleeve has the band portion 69 that extendcoaxial with the wall portion 66 to retain the free end 64 of the innerwall 61 frictionally in engagement with the reservoir tube 46, theshoulder 63 preventing the sleeve 65 and the wall 61 from movingdownwardly toward the base end of the shock absorber when fluid underpressure, such as air, is applied within the chamber space 54. Thesleeve 65 extends substantially into engagement with the cap 52, asshown in FIGURE 3.

The outer wall portion of the flexible tubular wall structure has thefree end '70 thereof attached to the lower end portion 71 of the tubularmember 51 by a nonexpansible metal ring 72 which frictionally retainsthe wall end portion in friction engagement with the wall portion 71.The wall portion 71 is in the form of a truncated cone so that fluidunder presure applied within the chamber space 54 tending to urge theouter wall portion 62 downwardly will tighten the friction engagement ofthe end wall portion 70 with the wall portion 71.

The lower end of the wall portion 71 has an inwardly turned wall portion75 that has its terminus end in close proximity to the inner wall 61 ofthe flexible tubular wall structure when the shock absorber is incomplete collapsed position as shown in FIGURE 3 so that when the wallmember 51 reciprocates relative to the reservoir tube 46, onreciprocation of the rod 33, the outer wall portion 62 will not tend toturn inwardly into the chamber space 54 and thereby become bound betweenthe lower end of the tubular member 51 and the inner wall 61 or theguide wall 65 that is provided at the upper end of the shock absorber. Aconduit connection '76 is provided in the tubular wall 51 through whichfluid under pressure is supplied into chamber space 54 and through whichpressure fluid is exhausted from the chamber space 54 under control ofsuitable valving herein after described.

From the foregoing description it will be apparent that the shockabsorber 30 of the combination shock absorber and air spring unit canfunction in conventional manner as a shock absorber when the air springunit is deflated, or depressurized, and when the air spring unitreceives fluid under pressure, such as air, the air spring unit will aidthe main springs 16 and 17 in resilient support of the sprung mass onthe unsprung mass of the vehicle, the shock absorber still retaining itsnormal function.

From the foregoing description it will be apparent that when the airspring unit 25 is operated in a deflated or depressurized condition,that is when the air pressure in the chamber space 54 is at atmosphere,or less than atmosphere, the outer flexible wall 62 will engage theinner wall portion 61 of the flexible tubular wall structure so that thewall surfaces rub against one another during reciprocal movement betweenthe wall portions 61 and 62. Also, it will be apparent that if the walls61 and 62 are in engagement, the radius of curvature of the return bendportion 63 will be extremely small, which produces undue stresses in thewall structure in the return bend portion 63. Both of these featurestend to reduce the life of the resilient flexible tubular wall structurecomprised of the walls 61 and 62.

In this invention therefore there is provided a control which allows formanually controlled or actuated inflation or deflation of the pressurechamber 54 of the air spring unit, but which prevents thedepressurization of the chamber 54 below a predetermined minimumpressure value, at which, just sufficient fluid pressure is retained inthe chamber 554 to maintain the walls 62 and 61 of the flexible tubularwall structure out of physical engagement during the reciprocation ofthe wall structure, which follows the reciprocation of the shockabsorber. Since the walls 61 and 62 will not be in engagement with oneanother, abrasion of the wall by rubbing contact will be eliminated.Also, since there will be a small amount of inflation pressure retainedin the chamber 54, the radius of curvature of the return bend 63 willnot be so sharp and therefore will relieve the flexing stresses in thereturn bend portion.

The device is illustrated in FIGURE 3 in a condition in which apredetermined minimum inflation pressure is retained in the chamber 54,the flexible walls 61 and 62 being shown out of engagement.

A control device to provide for manually actuated inflation or deflationof the air spring unit and to provide for control of the minimumpressure value to be residually retained in the chamber 54 is moreparticularly illustrated in FIGURE 4.

The control device illustrated in FIGURE 4 consists of a valve body 5%having an internal chamber 81 provided with a port 82 at one end thereofand a port 83 at the opposite end. The port 53 carries a fitting 84 thatconnects with the tube 76 for supplying fluid under pressure to thechamber space 54 of the combination shock absorber and air spring unitand through which fluid under pressure is exhausted from the chamberspace 54.

The inlet port 82 is supplied with a manually operated or actuated inletand exhaust control valve 85 that may be in the form of a conventionaltire valve. The valve 85 consists of a threaded body 86 received in thethreaded bore 37 in the port 82. The body 86 carries a sleeve member 88that, in turn, carries a seal member 8% adapted to seat in the portopening 9t) when the valve body 86 is threaded into the position shownin FIGURE 4. A valve stem 91 extends through the valve body 86 and thesleeve 83 and has a valve element 92 on the lower end thereof engagingthe valve seat 93 to close the internal port 94 through the valve 85.The valve stem fll holds the valve element flZ on its seat 93 by theengagement of the spring 95 between the lower end of the sleeve 88 andthe enlarged head 96 on the valve stem. A sealing cap 97 is threadedlyreceived on the upper end of the body of the valve 89, by the threadedportion flit, to sealingly close the port 82 when the cap 97 is in theposition illustrated in FIGURE 4.

Obviously, when the suitable nozzle is applied to the upper end of thevalve body Stl, air under pressure or other suitable gas under pressurefrom a suitable pressure source, conducted through the nozzle that isapplied to the end of the valve body, will cause the valve stem 91 tomove downwardly to move the valve element 92 away from its valve seatand allow fluid under pressure to enter into the chamber 81. Similarly,when the valve stem is manually pushed downwardly, the fluid underpressure in chamber 81 can be exhausted back through the valve $5therefore being and functioning like a conventional tire valve.

The chamber 81 in the valve body as includes an enlarged chamber portionltlti that receives a valve men ber 161 that forms an automaticallyoperating residual pressure control valve for shutting off exhaust ofpressurized fluid from the chamber space 5-4 when fluid pressure in thechamber space 54 reaches a predetermined minimum value.

The valve member till has a resilient rubber-like disk 102 on the bottomface thereof, the disk being provided with a central opening 103. Thebottom wall lfld of the valve element ltil is provided with a pluralityof ports 105 that are out of alignment with the central opening it)? inthe rubber-like valve disk M2. The rubber-like valve disk N92 isretained on a valve seat 1% by means of a compression spring lldi. Thevalve seat ltlfi provides a central chamber 10$ that communicates withthe fluid flow port 83 and thereby the conduit 76 that connects with thechamber space 54 of the air spring unit 25.

Normally, the valve element 101 retains the rubber-like valve disk 1&2on its seat ltlfi in the position shown in FIGURE 4 regardless ofwhether the chamber space 54 or" the air spring 25 is pressurized ordepressurized. The conduit '76 is in fluid flow communication with thechamber space 81 of the valve 86 when fluid under pressure is beingsupplied to the chamber space 5-4 since the valve 92 will be lifted fromits seat 93 and the air under pressure can flow from the chamber 81 downthrough the openings E95 and the valve element ltil to deflect therubbenlike valve member 102 downwardly with the result that the fluidunder pressure flows through the central opening 163 into the conduit 76for supply to the chamber space 54 of the air spring so long as thefluid pressure source, or air pressure source, is connected with the airspring. The degree or value of air pressure or fluid pressure suppliedinto the chamber space 64 is therefore under control of manual actuationof the operator and the maximum air pressure or fluid pressure availableat the source of supply. The operator of the vehicle can visuallydetermine when suflicient air pressure has been supplied into thepressure chamber 54 by inspecting the level condition of the vehiclerelative to the road.

When it is desired to deflate the air spring unit 25, the operator ofthe vehicle can manually move the valve stem 91 downwardly to move thevalve element 92 from its seat and thereby open the passage for exhaustof fluid under pressure from the conduit 76. This will be asuncontrolled exhaust of fluid pressure from the chamber space 54 exceptas for the manual control of the operator, and except for the automaticoperation ofv the residual pressure control valve 101.

So long as the fluid pressure in the conduit 76 is greater than theeffect of the compression spring 167, the valve element 102 will belifted from its seat 106 whenever the valve stem 91 is moved inwardly toopen valve element 92. This will allow free and uncontrolled exhaust offluid under pressure from the pressurizing chamber 54 of the air springunit 25 until the fluid pressure in the chamber '4 and therefore in theconduit 76 falls to a predetermined loW value equal to the eliect of thecompression spring 107 on the valve element 101. At this time the valveelement 101 will seat the valve disk 1102 on the seat 1% and therebyprevent further depressurization of the air chamber space 34 of the airspring unit 25 and thereafter retain a residual fluid pressure in thechamber space 54 that is sufficient to prevent the outer wall 62 and theinner wall 61 of the flexible tubular wall structure from engaging oneanother or preventing the wall 62 from engaging the guide wall 65 duringthe reciprocation of the flexible tubular wall structure relative to theshock absorber 30. Obviously, whenever the cap 97 is placed upon thebody of the valve 8%, the system will be sealed so that once the minimumpressure value has been established in the chamber 54, assuming nofurther leakage in the system, the established minimum pressure willthereafter be retained in the chamber It has been determinedexperimentally that a pres sure value of approximately 10 lbs. persquare inch is sufficient in the pressurizing chamber 54 of the airspring unit 25 to maintain suflicient inflation in the air spring unit25 to prevent engagement of the walls 61 and 62 in the normal reciprocalmovement of the shock absorber, and that this low pressure valueretained in the chamber 54 does not have any substantial etiect on thespring eflect of the main springs 16 and 17 of the vehicle so that thenormally engineered ride effect of the springs 16 and 17 is not upset bythe low air pressure value that is retained as residual pressure in thechamber 54 of the air spring units 25.

While the embodiments of the present invention as herein disclosedconstitute preferred forms, it is to be understood that other formsmight be adopted.

What is claimed is as follows:

1. A valve for controlling flow of fluid under pressure and exhaust offluid under pressure respectively to and from an air spring and forretaining in the air spring a residual fluid pressure of a predeterminedminimum value, said valve comprising, a tubular valve body having animperforate outer diameter forming an internal chamber, said tubularbody having a first Open end and a second open end in communication withsaid internal chamber, first valve means in one end of said tubular bodyincluding a valve element and first spring means for urging said valvingelement into a position for closing one of said end openings andoperable manually to open said one open end for pressure fluid flow ineither direction through said internal chamber, and a second valve meansin the opposite end of said tubular body for controlling pressure fluidflow through the other open end of said valve body, said second valvemeans including second Spring means and a valving element having oneposition for allowing pressurized fluid flow from said internal chamberthrough said other open end to a pressurizable chamber, said valvingelement having a second position for allowing exhaust of pressurizedfluid from the pressurizable chamber into said internal chamber and athird position closing said other open end against exhaust ofpressurized fluid flow from the pressurizable chamber into the internalchamber upon the occurrence of the predetermined minimum pressure valuein the pressurizable chamber.

2. A valve for controlling flow of fluid under pressure and exhaust offluid under pressure respectively to and from a pressurizable chamberand for retaining a residual pressure of a predetermined minimum valuein the chamber upon exhaust flow of fluid therefrom, said valvecomprising, a tubular valve body having an imperforate outer diameterforming an internal chamber,

said valve body having an opening through either end thereof incommunication with said internal chamber, valve means in said tubularbody at one end thereof including means urged to a first position forclosing the opening through one end of said tubular body and operablemanually to an open position for allowing pressure fluid flow in eitherdirection through the opening at said one end of said valve body to andfrom said internal chamber, and a second valve means in said tubularbody at the opposite end thereof for controlling pressure fluid flowthrough the opening at the other end of said tubular body, said secondvalve means including a first valve member urged resiliently to closesaid other end opening against pressure fluid flow from said internalchamber to a pressurizable chamber and to open said other end openingfor exhaust flow of pressurized flow from the pres-- surizable chamberto said internal chamber, said second valve means having a wall providedwith passageway means therethrough for fluidly connecting said internalchamber with the second end opening and including a resilient valvingmember on said wall for closing said passageway means against exhaust ofpressurized fluid flow from said other end opening into said internalchamher while opening said passageway means for flow of prossurizedfluid from said internal chamber to' said other end opening.

3. A valve for controlling flow of fluid under pressure and exhaust offluid under pressure respectively to and from an air spring and forretaining in the air spring a residual fluid pressure at a predeterminedminimum value,

said valve comprising, a tubular valve body having an imperforate outerdiameter forming an internal chamber, said tubular body having a firstand second open end in communication with said internal chamber, valvemeans in one end of said tubular body including a spring and a valveelement spring urged thereby to a position for allowing pressure fluidflow in either direction through said one open end to and from saidinternal chamber so long as the valve means is held open against thespring pressure urging the same to a closed position, and a second valvemeans closing the other of said open ends, said second valve meansincluding a spring and a body member having a flexible valve disk on onewall thereof with the said body member having ports through the said onewall for flow of fluid pressure in one direction through the said bodymember outwardly of said internal chamber through the other open end ofsaid valve body, said valve disk being flexed away from the said wallfor the pressure fluid flow from said internal chamber through saidother open end, a valve seat in said other open end, said flexible valvedisk being normally urged against said valve seat by spring pressureapplied to the body member of said valve means, said valve disk havingan opening therein misaligned with the ports in said one Wall to providefor the aforesaid flow of pressure fluid through said valve means, saidbody member and the flexible valve disk carried thereby being raisedfrom said seat by pressure flow from said other open end to saidinternal chamber in the opposite direction until pressure of the fluidflowing in the said opposite direction reaches a predetermined minimumvalue at which said spring of the-valve means urges said valve diskagainst said seat to close the said other open end against further fluidflow to said internal chamber.

References Cited by the Examiner UNITED STATES PATENTS 1,120,088 12/14Saam 137-614.2 XR 2,133,575 10/38 Rosenberg 137493.2 2,147,084 2/39Bouchard 137-61419 XR 2,789,578 4/51 Goepfrich 137493.1 2,954,796 10/60Marshall l37226 LAVERNE D. GEKGER, Primary Examiner.

ISADOR NEIL, Examiner.

1. A VALVE FOR CONTROLLING FLOW OF FLUID UNDER PRESSURE AND EXHAUST OFFLUID PRESSURE RESPECCTIVELY TO AND FROM AN AIR SPRING AND FOR RETAININGIN THE AIR SPRING A RESIDUAL FLUID PRESSURE OF A PREDETERMINED MINIMUMVALUE, SAID VALVE COMPRISING, A TUBULAR VALVE BODY HAVING AN IMPERFORATEOUTER DIAMETER FORMING AN INTERNAL CHAMBER, SAID TUBULAR BODY HAVING AFIRST OPEN END AND A SECOND OPEN END IN COMMUNICATION WITH SAID INTERNALCHAMBER, FIRST VALVE MEANS IN ONE END OF SAID TUBULAR BODY INCLUDING AVALVE ELEMENT AND FIRST SPRING MEANS FOR URGING SAID VALVING ELEMENTINTO A POSITION FOR CLOSING ONE OF SAID END OPENINGS AND OPERABLEMANUALLY TO OPEN SAID ONE OPEN END FOR PRESSURE FLUID FLOW IN EITHERDIRECTION THROUGH SAID INTERNAL CHAMBER, AND A SECOND VALVE MEANS IN THEOPPOSITE END OF SAID TUBULAR BODY FOR CONTROLLING PRESSURE FLUID FLOWTHROUGH THE OTHER OPEN END OF SAID VALVE BODY, SAID SECOND VALVE MEANSINCLUDING SECOND SPRING MEANS AND A VALVING ELEMENT HAVING ONE POSITIONFOR ALLOWING PRESSURIZED FLUID FLOW FROM SAID INTERNA CHAMBER THROUGHSAID OTHER OPEN END TO A PRESSURIZABLE CHAMBER, SAID VALVING ELEMENTHAVING A SECOND POSITION FFOR ALLOWING EXHAUUST OFF PRESSURIZED FLUIDDFROM THE PRES-SURIZABLE CHAMBER INTO SAID INTERNAL CHAMBER AND A THIRDPOSITION CLOSING SAID OTHER OPEN END AGAINST EXHAUST OF POSITION CLOSINGSAID OTHER OPEN END AGAINST EXHAUST OF THE INTERNAL CHAMBER UPON THEOCCURENCE OF THE PREDETERMINED MINIMUM PRESSURE VALUE IN THEPRESSURIZABLE CHAMBER.